Good job, commercial vacuum pots are pretty expensive and you prove that handy man and components costs just few bucks. I am also impressed that bulb not break from direct flame.
Perhaps you should be concerned about ingesting the metal residues from the inside of the bulbs as well as the bases, that the acid in coffee will dissolve into solution. In general, don't eat or drink out of anything that wasn't made for it. Much of the brightly colored, decorative (not cookware) "pottery" from China has super high lead content. No danger though, unless you try to eat or drink out of it - then it's very very dangerous! Just a thought. Love your vids!
How to Make • Coffee Machine Vacuum Lightbulbs
